Creating Calculated Categories

You can use calculated categories to add commonly requested calculations to your model, such as month-by-month percent growth or market share. Because the calculations are computed in Cognos® Transformer and then added to the PowerCube, the results immediately appear in the OLAP reporting component for every measure specified in the cube.

For example, you can base a calculation on the special time categories Current Month and Last Month. You use the percent-growth function to create a new calculated category named Monthly Growth which shows the percentage change between these two items for all measures included in your PowerCube.

Category calculation is based on a formula and a set of categories to which the formula applies. You compose the formula with the help of an expression editor and a selection list of functions and operators. You then specify the categories to which the formula applies: either a single category, a category set (if supported for that function), or all categories in the level. Sets are convenient category groupings that may be from the same level, or from different levels.

You can view a category calculation by opening the Calculated Category property sheet or by using the Show Category Calculation command on the Diagram menu.

The formula varies according to the context of each category. The applicable formula can only reference another single category, not a category set or a level. Separately defined categories are useful when you want to create special groupings, such as 'Japan'+'Hong Kong'. Calculated categories are identified in the Categories diagram by their own icon .